In conventional varnish treatment methods for stators, such as that described in Japanese Patent Laid-Open No. HEI 07-213029 (Gazette), for example, varnish is dripped onto surfaces of coil ends of a stator winding from radially outside while rotating a stator heated to a predetermined temperature, then low-pressure air is blown onto the coil ends from radially outside before the viscosity of the varnish increases, and then the varnish is hardened in a drying oven. The varnish dripped onto the surfaces of the coil ends penetrates into the coil ends by capillary action through gaps between the coils of the stator winding, but if the drip rate of the varnish is low, the penetration speed of the varnish is reduced, and the varnish does not penetrate the coil ends completely. Thus, after dripping the varnish, the varnish is forcibly made to penetrate inside the coil ends by blowing the low-pressure air onto the coil ends. It is claimed that the varnish can thereby be made to penetrate the coil ends completely, even if the drip rate of the varnish is low.
However, in conventional varnish treatment methods for stators, one disadvantage has been that an air generator is required, making the varnish treatment process an extremely large-scale operation.